No. 16 Nationals: 15th in a series counting down to spring training. Next: Blue Jays

Bryce Harper hasn't played a day in the big leagues, and unfortunately for him there is only one way to go. It is opposite of up.

But if you want to bet on Harper as the second coming of Corey Patterson and Oddibe McDowell, you haven't been paying attention. The teenage hitter is a stone-cold killer with a bat in his hands, which is why fans in Washington will flock to Viera, Fla. — one of the last remaining spring training outposts — to see him and old man Stephen Strasburg (24 in July) next month.

Harper's as real as death, taxes and rush-hour traffic. As an 18-year-old, he put up an .894 OPS in his first pro season and then scorched the Arizona Fall League, driving in 26 runs in 25 games and assembling a slash line of .333/.400/.634.

Baseball America, a historically conservative publication, gives him an 80 on the scouts' scale of 20-80, billing him as something of a big deal, as the T-shirts say.

"Harper looks like a sure-fire superstar in the making,'' according to Baseball America's 2012 Prospect Handbook, "and he has a very real chance to develop into the best all-around player in baseball.''

The only real question with Harper is how fast will he come? Left to his own devices, he would like to convince Nationals general manager Mike Rizzo and manager Davey Johnson that he's as ready as he ever will be. He would love to line up alongside Strasburg and the Nationals' collection of young players on Opening Day.

That's probably not going to happen, if only because Rizzo is committed to giving Adam LaRoche a chance to develop some trade value as his first baseman, which for the moment has Michael Morse in left field. Soon enough, though, Harper is going to take either Roger Bernadina's spot in center field or join the Occupy Right Field movement, with Jayson Werth moving to left and Morse going back to first, where he started 82 games last year while LaRoche was sidelined with a shoulder injury.

Harper's debut is going to be an event, whenever it comes. But while he will get his feet wet in 2012, his real impact probably won't be felt until '13.

No matter how talented a hitter may be, it's just really hard to tattoo big league pitchers before your 20th birthday.

Since the Cubs' Phil Cavarretta in 1935, only five players have had 500-plus at-bats in a season before turning 20: Buddy Lewis, Bob Kennedy, Al Kaline, Rusty Staub and Robin Yount. Only five ever have hit double-figure home runs before turning 20: Mel Ott, Mickey Mantle, Ed Kranepool, Tony Conigliaro and Ken Griffey Jr.

History shows that it is often much easier the second time around for players whose talent catapulted them to the big leagues far ahead of their peers.

Kaline hit .276 with a .652 OPS in 138 games as a 19-year-old for the 1954 Tigers. He won a batting title the next year, while also increasing his home run total to 27, which allowed him to finish second in the MVP race.

Mantle finished third in the MVP race the season after he hit .267 with a promising .792 OPS in 96 games for the '51 Yankees. Alex Rodriguez, who batted .232 in 48 games as a 19-year-old, should have won the American League MVP as a 20-year-old. He hit .358, and led the league with 141 runs and 54 doubles, but two Seattle writers followed Lou Piniella's suggestion to vote for Griffey Jr., which allowed the Rangers' Juan Gonzalez to win.

There's a lesson here. When Harper and, say, third baseman Ryan Zimmerman put up monster numbers for the Nationals, Johnson should be careful not to influence voters. He will have a full season to consider his options, as 2012 will be about Harper's arrival, not his immediate jump into the elite category.

And furthermore

•The Nationals declined to make a huge offer to Prince Fielder for two reasons: Zimmerman is two years away from free agency, and potentially could be moved to first base to facilitate an infield that includes David Espinosa, Ian Desmond and Anthony Rendon, Washington's first-round pick in the 2011 draft, and there is no designated hitter rule in the NL.

•Catcher Wilson Ramos, obtained in a terrific trade with the Twins for closer Matt Capps, will have an unusual story to tell this spring after being kidnapped this winter. Facing Tim Lincecum's fastball might be a little less scary this season.

•Gio Gonzalez could join Roy Halladay, Cole Hamels, Clayton Kershaw, Matt Cain and Yovani Gallardo on the list of leading candidates for the Cy Young award after arriving from the A's. His ERA has decreased in each of the last three seasons, to 3.12 a year ago. He's expected to be a key on the staff when the Nationals become contenders, as he signed a five-year, $42 million contract extension last month.

•Mark DeRosa is a great guy, and it would be nice to see him bounce back from 21/2 lost seasons battling wrist issues. He and Mike Cameron, another respected veteran, will provide a major lift in the clubhouse if they can play well enough to carry themselves in their usual style.